A colon polyp is a growth inside the colon. While most are harmless, there is a correlation between colon polyp size and cancer risk. Colon polyps that continue growing, or that become very large, may become cancerous, so doctors remove them.
Anyone can develop colon polyps, and about 6% of children have them. However, the risk of colon polyps and colon cancer increases with age. About a third of people over 50 have polyps. More than
Colon polyps grow very slowly and often do not cause symptoms. Regular colon cancer screenings can help detect them before they become cancerous.
Read on to learn more about colon polyp size and cancer risk, including some other potential symptoms of colorectal cancer and treatment options.
Cancer happens when cells grow out of control, creating tumors. Colon cancer is no exception.
Doctors divide colon polyps into
- tubular: a tube-like projection
- villous: a finger-like projection
Both can be cancerous or precancerous, but larger growths are more likely to be villous.
An adenoma is a colon polyp that may turn into cancer.
There is no set size at which a polyp will become cancerous, nor any particular size that is always cancerous. Even among large polyps, the majority are not cancerous.
A 2018 study of polyp size and cancer included 550,811 polyps. The majority (81%) were 1–9 mm in diameter. Only a small percentage of polyps (3.4%) were cancerous.
However, cancer rates were highest among the largest polyps.
The percentage of polyps that were cancerous, by size, was as follows:
|Polyp size||Percentage cancerous|
Another 2018 study supports this finding. The study analyzed a total of 15,906 polyps. Among polyps larger than 30 mm in size, 4.6% were cancerous. Incidence of cancer in polyps less than 5 mm in size was 0%.
Colon polyps grow slowly, and people with either polyps or colon cancer may not have any symptoms. This is why colon cancer screenings are so important.
People who do have symptoms
- rectal bleeding
- bleeding during a bowel movement
- feeling like their bowels are not empty after a bowel movement
- frequent constipation or diarrhea
- pain in their stomach
- changes in bowel habits
During a polypectomy, a doctor removes the polyp. This allows them to test the polyp for cancer and prevent noncancerous and precancerous polyps from growing and developing into cancer.
Depending on the number and size of polyps, a doctor may recommend additional or more frequent colon cancer screenings.
If the polyps are cancerous, a doctor may recommend surgical resection. This is the removal of a portion of the colon to prevent cancer from continuing to grow.
Most early stage cancers do not require chemotherapy if a doctor is able to remove the cancer. However, more advanced stages may require chemotherapy.
Some types of colon cancer respond to targeted immunotherapy drugs. Immunotherapy supports the immune system to recognize and treat cancer. The right treatment depends on:
- the cancer itself
- the health of the person with cancer
- how advanced the cancer is
- whether it has spread to other areas of the body
The right treatment also
Early removal of colon polyps has a good outlook. However, people with a history of polyps may develop more polyps.
Lynch syndrome or familial adenomatous polyposis (FAP) are genetic predispositions that also
However, in the early stages, if a doctor is able to completely remove the cancer, the outlook is good and it may be possible to cure the cancer. A person may need ongoing cancer screenings for the rest of their life.
Many people may avoid or delay having a colonoscopy. However, it remains a highly effective tool for detecting colon polyps and the early stages of colon cancer.
These polyps typically grow slowly, allowing plenty of time for detection and removal before they become cancerous. Without screening, they may go undetected, allowing cancer time to grow and spread.
It is much easier to treat polyps and early stage cancer than it is to treat advanced colon cancer. People over age 50, as well as people who have a high risk of colon cancer, should discuss a screening test with a doctor.
People should also note that there are other colon cancer screening options available.